This invention relates to a photographic material, particularly to a photographic material which comprises a synthetic plastic film, a polyolefin (abbreviated as "PO" hereinafter) layer provided on one surface of the plastic film, an image forming layer provided on said PO layer and layer (A) which contains at least one of carboxy-modified polyethylene (abbreviated as "CPE" hereinafter), ethylene-ethyl acrylate copolymer (abbreviated as "EEA" hereinafter), ethylene-vinyl acetate copolymer (abbreviated as "EVA" hereinafter) and PO and which is provided on another surface of the synthetic plastic film opposite to the image forming layer side, the surface of said polyolefin layer which contacts with the image forming layer being a roughened surface and the surface of the layer (A) being a mirror-like surface.
As a support for photographic materials, for example, lithographic printing plates, there are used metallic plates such as aluminum plate, zinc plate, etc., plastic films, paper materials, among which suitable supports are chosen considering printing endurance and other printing characteristics such as ink stains formed while printing, adhesion strength between image forming layer and support, and besides production cost, handling properties.
Recently, automatic plate making and automatic printing systems have been remarkably spread in office light printings and lithographic printing plates excellent in printing endurance and suitable for various plate-making processes have been used.
Usually, plate-making from lithographic printing plate is carried out by giving imagewise exposure from the top side of the plate (i.e. image forming layer side with reference to the support) by a process camera having a reversing mirror (often referred to as "top face exposure method" hereinafter). In this case, the support of lithographic printing plates may not be transparent and various metallic plates and paper materials may also be used as the support. However, when the plate-making is carried out by giving an imagewise exposure from the back side of the photographic material for lithographic printing plates (i.e. the side opposite to the image forming layer) by a process camera with no reversing mirror (often referred to as "back face exposure method" hereinafter), the support is required to be transparent and so metallic plates and paper materials cannot be used as the support and plastic films high in transparency are used.
The photographic materials of this invention can be used not only for the ordinary lithographic printing plates of the top face exposure type, but also for especially the lithographic printing plates of back face exposure type. The so-called back face exposure method according to which an imagewise exposure is carried out from the back side of the photographic materials by a process camera containing no reversing mirror is disclosed, for example, in Japanese Patent Unexamined Publication (KOKAI) No. 89007/73.
Because of excellent transparency, plastic films are used for various photographic materials and are also suitable as the support of photographic materials for lithographic printing plates of back face exposure type.
For supports of photographic materials for lithographic printing plates which are strongly required to have characteristics such as elongation and stiffness, polyester films are suitable among various plastic films such as triacetate films, polycarbonate films, polystyrene films, polypropylene films, polyvinyl chloride films, polyester films and the like.
Photographic materials, especially those for lithographic printing plates are used under high printing pressures and in highly viscous state and hence the surface of support and image forming layer (which might be referred to as "an emulsion layer" hereinafter) must sufficiently adhere to each other. However, due to poor surface activity of polyester films per se, it is difficult to directly coat the emulsion on the surface of the films and besides, even when the emulsion is coated after surface activation treatment such as corona discharge treatment, significant problems such as peeling of emulsion layer (frilling) occur during a sequence of photographic treatments due to difference in heat shrinkage of polyester film and the emulsion layer.
Adhesion between the polyester film and the emulsion layer can be increased by providing on the polyester film a resin layer of other resins such as polyolefins which are thermoplastic resins.